Joe Hart the lone bright spot in Manchester City's struggling defence

ESPN FC's Steve Nicol and Alexis Nunes discuss who will be heading out the Man City exit door this summer.

Joe Hart's future at Manchester City has probably never been more secure than it is right now. With Pep Guardiola likely to make a raft of changes at the club when he takes over from Manuel Pellegrini in the summer, the chances are he won't be looking for a new number one goalkeeper.

As defensive woes plague the team, it's the England international who is profiting. Without Vincent Kompany in the side this season, the back four have looked at best nervous and at worst almost fictional, as a number of teams have wrecked all sorts of havoc in and around City's box.

The 3-1 defeat against Leicester highlighted some of the side's deficiencies. The defensive line was frequently disjointed, as one of Nicolas Otamendi or Martin Demichelis pushed up, while the other didn't; meanwhile, both Aleksandar Kolarov and Pablo Zabaleta struggled with the pace of the Foxes' attacks. The less said about the absent central midfield and Otamendi's desire to dive in with two feet to completely sell himself the better.

Behind all of that disorganisation, Hart was pretty much the only thing that stopped the result from becoming more embarrassing, as he pulled off a string of good saves to keep the visitors' tally to three. Jamie Vardy should have twice found the net and didn't, as the goalkeeper was off his line quickly to block.

While Manchester City's defence have struggled this season, Joe Hart has been a rock in goal for manager Manuel Pellegrini.

It feels like Hart has been sturdy for some time, but it's not actually that long ago that others were being eyed up as potential replacements. As late as May 2013, it was reported that City were considering then-Stoke goalkeeper Asmir Begovic. That deal reportedly fell through when former manager Roberto Mancini was sacked.

Hart is a key player to City and one of the few who has major links with both the old and the new eras in Manchester. He was signed for an initial £600k from Shrewsbury in 2006, and made his debut in a team that struggled to win games -- that 2006-07 campaign saw 10 home league goals all season.

The goalkeeper found his feet as the club changed season by season. A superb showing in the 0-0 draw with Tottenham on the opening day of 2010-11 strengthened his position as he returned from a loan at Birmingham. His future was then never in doubt.

A year later, he produced some fine saves -- notably in 1-0 wins over Arsenal and Aston Villa and a 2-0 win at Newcastle -- to help his team to the title.

They say pride comes before a fall and with Roy Keane branding the goalkeeper "arrogant", the pressure was mounting as mistakes crept into his game throughout 2013, culminating in a calamitous mix-up with Matija Nastasic in a 2-1 loss at Chelsea in October of that year.

Why he charged off his line is still a mystery, as Nastasic had the situation under complete control, only for Fernando Torres to be gifted the winner. However, Hart came back stronger and he's since grown into perhaps the best goalkeeper in the Premier League, after being dropped in November 2013 for seven top-flight matches.

Under Pellegrini, City's defence hasn't always been top notch, but having an on-form Hart behind it has helped their continued bids for success. At times when the club has been down on its luck, Hart has bailed them out: The fingertip save in the 3-2 win at Everton in 2014; the touch over the bar in the 4-2 victory at Swansea in 2015, and his one-man show in a 1-0 loss at Barcelona last season all spring to mind.

Two of the team's biggest issues this season have been conceding soft goals and not taking their chances while ahead. That they're still in with a chance of winning the Premier League title, and that they won their Champions League group quite comfortably in the end, says a lot about the work that Hart has been doing at the back.

The truth is that City do not defend well -- and their goalkeeper has been instrumental in minimising the damage that an unsettled back four has done.

One criticism that could be levelled at the club is that the most important players in the side are the same now as they were in the title-winning team of 2011-12. Hart, Vincent Kompany, David Silva, Sergio Aguero and to an extent Yaya Toure still form the basis of the squad and not enough has been done to bring in players to ease the burden.

That might change with Guardiola in the dugout, but the first name in his squad list MUST be Hart's. He's the only player who can remember how desperate things were at the club a decade ago and he's one of the few who understands what it means to the fans.

On top of that, the last season-and-a-half has shown just how impressive he can be.

David Mooney is ESPN FC's Manchester City blogger. Twitter: @DavidMooney